This invention relates to a damper disc applicable to friction clutch discs of land vehicles, construction machineries, civil engineering machineries, industrial equipments or the like, and especially suitable for large-sized and medium-sized friction clutch discs.
In a type of known damper discs, a sub-plate is arranged between a radial flange of a hub splined to an output shaft and each of side plates which are a clutch plate and a retaining plate. A first friction member having small frictional force is arranged between the hub-flange and each sub-plate, and a second friction member having large frictional force is arranged between each side plate and each sub-plate. In this construction, when small torque is transmitted, and therefore the relative torsion angle between the hub-flange and the side plates is small, slide occurs on the surface of each first friction member, so that small hysteresis torque occurs. When the transmitted torque increases to large value, and thereby the torsion angle increases to large value, slide occurs on the surface of each second friction member, so that large hysteresis torque occurs. In the disc in which the hysteresis torque changes as stated above, noises can be prevented during both idling and high power driving.
However in this known type of the damper disc, since the sub-plates are arranged between the hub-flange and the side plates, the distance between two side plates is long. Therefore the side plates may not stably support the ends of torsion springs disposed in openings of the sub-plates and the side plates, which may cause dispersion in the characteristics of the twisting operation and may lower the reliability of products.
Further in said disc, since each second friction member is pressed strongly against a surface of each side plate, and other surface of each side plate is not supported by any member, the side plates may be deformed by the pressure into tapered or waved shape. Therefore the desired hysteresis torque may not occur, and the side plates, especially if they are thin, may be destroyed. This disadvantage occurs remarkably in the large-sized and medium-sized discs, in which the second friction members are pressed very strongly so that especially large hysteresis torque may occur.
Accordingly, it is an object of the invention to provide an improved damper disc, wherein each side plate is arranged between each sub-plate and a flange of a hub splined on an output shaft.
Other and futher objects, features and advantages of the invention will appear more fully from the following description of the preferred embodiment of the invention.